Since the advent of residential and commercial air conditioning systems, many ingenious apparatus and processes for cooling ambient air temperatures within buildings have been created. One general concept is almost universally utilized throughout such systems. That concept is to use a refrigeration process to change a heat storage medium from a liquid state to a frozen solid state, and then use the coolness stored within the frozen medium to cool the ambient air of the building.
For example, many commercial ice storage or thermal storage air-conditioning systems typically include a large storage container that is filled with a heat storage medium such as liquid water, a fluid brine solution, or other phase-change material (PCM). For purposes of easy understanding the term "water" will be used to indicate any appropriate heat storage medium, including, but not limited to, water, a brine solution, or other phase-change material (PCM).
A section of piping is placed within the storage container so that a substantial portion thereof is immersed within the water. The piping is connected to a refrigeration system.
In a standard refrigeration system liquid refrigerant at high pressure is passed through an expansion valve to an area of low pressure called an evaporator. As the liquid refrigerant passes from the expansion valve into the evaporator some of the refrigerant turns from a liquid to a gaseous vapor. As a consequence of the liquid refrigerant turning to a vapor, the refrigerant loses heat and becomes colder.
After the refrigerant passes through the evaporator, the refrigerant enters a compressor and is subjected to a high pressure. The compressor pumps the refrigerant to a condenser. As the refrigerant flows through the condenser, the high pressure causes the vapor to condense back to a liquid. As this process occurs, heat is expended and the condenser becomes warm. This process is known as refrigeration.
During a charging phase of the thermal storage system, the piping, that is immersed within the contained water, functions as an evaporator. Consequently, liquid water that surrounds or contacts the piping is quickly cooled and frozen to form ice. As the charging phase of the system continues, the amount of ice surrounding the piping increases until nearly the entire volume of contained water forms a large block of ice.
During the charging phase of the thermal storage system, the condenser is generally located outside the building so that heat generated during the condensing phase can be expelled into the atmosphere, whereupon the refrigeration process begins again.
During a discharging phase of the thermal storage system, the process of passing liquid or brine solution, and/or the evaporated refrigerant through the system is generally reversed. Consequently, the piping that is located within the storage container and is imbedded within a nearly solid block of ice, no longer functions as an evaporator to cool the water. Rather, such piping functions as a heat pump, condenser, or heat exchanger, to remove stored thermal energy to cool the building. For example, heated or warm liquid refrigerant can be passed through the piping, whereupon the liquid refrigerant and piping are cooled by the surrounding block of ice. As the heated liquid refrigerant and surrounding piping is cooled, the block of ice is slowly melted. Since the block of ice is so large, this cooling effect may continue for a substantial period of time. The cooled liquid or refrigerant can then be used to cool the ambient air temperature of the building.
The following patents describe specific apparatus and processes related to air conditioning systems and heat exchangers: Kleist (U.S. Pat. No. 2,737,027, issued Mar. 6, 1956); Benedek et al. (U.S. Pat. No. 2,933,885, issued Apr. 26, 1960); Percival (U.S. Pat. No. 3,062,510, issued Nov. 6, 1962); Shinn (U.S. Pat. No. 3,163,209, issued Dec. 29, 1964); Angus (U.S. Pat. No. 3,653,221, issued Apr. 4, 1972); Boer (U.S. Pat. No. 3,960,207, issued Jun. 1, 1976); Roma (U.S. Pat. No. 4,054,980, issued Oct. 25, 1977); Schroder (U.S. Pat. No. 4,091,863, issued May 30, 1978); MacCracken (U.S. Pat. No. 4,294,078, issued Oct. 13, 1981); MacCracken (U.S. Pat. No. 4,403,645, issued Sep. 13, 1983); MacCracken (U.S. Pat. No. 4,565,069, issued Jan. 21, 1986); MacCracken et al. (U.S. Pat. No. 4,608,836, issued Sep. 2, 1986); MacCracken (U.S. Pat. No. 4,671,347, issued Jun. 9, 1987); MacCracken et al. (U.S. Pat. No. 5,005,368, issued Apr. 9, 1991); and Pardubice (Czechoslovakia Patent No. 123,424, issued 1967).
The inventor believes that the listed disclosures taken alone or in combination neither anticipate nor render obvious the present invention. Citation of these disclosures does not constitute an admission that such disclosures are relevant or material to the present claims. Rather, such relate only to the general field of this invention and are cited as constituting the closest art of which the inventor is aware.